1. Field of the Invention
The present invention relates to a power transmission device including a plurality of gear trains which establish a plurality of variable speed stages and a meshing mechanism which fixes gears constituting the gear trains to a shaft.
2. Description of the Related Art
Conventionally, there is known a power transmission device which includes a plurality of gear trains that establish a plurality of variable speed stages and a meshing mechanism that freely fixes gears constituting the gear trains to a shaft (for example, refer to Japanese Patent Application Laid-Open No. 2013-174284).
Moreover, the power transmission device is generally provided with a parking mechanism which inhibits the rotation of an output shaft by locking a parking gear in the case of switching to a parking range by a driver's shift operation (for example, refer to Japanese Patent No. 4506097).
When a vehicle transitions to a parking state in response to a driver's shift operation, an engaging portion engages with a parking gear, thereby causing a locked state in which the rotation of an output shaft is inhibited. Moreover, generally, when switching to a parking range by a shift operation, the driver is required to continue to depress a brake pedal. After the completion of switching to the parking range, the driver takes his/her foot off the brake pedal.
At this time, the parking gear is locked. In the case of parking on an uphill road or the like, however, the braked drive wheels are released and a vehicle moves to descend the inclined surface by a clearance of the engagement until the parking is locked. Thereafter, the vehicle weight is applied to the output shaft, thereby generating a torsional torque.
Therefore, in the case where the driver wants to preshift to a forward stage or other gear in preparation for the next startup, a synchronous meshing mechanism may be affected by a torsional torque, which may inhibit a transition to a connected state.